The 21-day clock on a DPN starts when it is issued, not when your client opens...

https://jeffreyknev582.yousher.com/what-does-a-lockdown-director-penalty-notice-actually-change-for-directors

The 21-day clock on a DPN starts when it is issued, not when your client opens the mail. Knowing the difference between lockdown and non-lockdown notices is vital to managing personal liability. Read this so you can triage fast and keep options open.